Designed by John Mauchly and J. Presper Eckert, the Electronic Discrete Variable Automatic Computer superseded the ENIAC. Its differences from the ENIAC were that it was binary rather than decimal, and it was a stored program machine. The EDVAC included automatic addition, subtraction, multiplication, programmed division, and automatic checking with an ultrasonic serial memory. It contained a dual memory unit. Its addition time was 864 microseconds while its multiplication time was 2900 microseconds. It also had almost 6000 vacuum tubes and 12000 diodes. The EDVAC was also used in the Ballistics Research Laboratory, just like its predecessor.